21 weeks pregnant

Your baby is the size of a

banana

21 Weeks Pregnant: Your Baby’s Development

Heart throb. Your baby's heartbeat is now loud enough to be heard through a simple stethoscope, but the beat can be difficult to distinguish from your own. Listen for the faster rhythm — a baby's heartbeat is 120 to 160 beats per minute, about twice as fast as your own. Many women think it sounds like galloping horses.

Snooze news. Your baby is already starting to sleep and wake in subtle cycles. Ultrasounds show that unborn babies may even settle into a favorite sleeping position.

21 Weeks Pregnant: Your Symptoms

Sore spots. Backaches, especially in the lower back, are quite common during pregnancy. Your growing uterus is shifting your center of gravity and pulling your lower back forward. Meanwhile, the hormone relaxin is loosening every joint and ligament in your body, which will allow your pelvis to expand when it's time for delivery.

Back savers. To help alleviate back pain, make these adjustments in your daily routine. Whenever you sit, use a footrest to elevate your feet slightly. If you need to stand for a long period of time, put one foot on a small stool to take some pressure off your lower back. Treat yourself to a warm bath for additional relief. If your backache won't go away, give your healthcare provider a call.